The present invention is related to explosive devices, especially those of a military nature, and is more particularly directed to a unique method for combining the blast shield with the forward charge in a tandem warhead system requiring a very long time delay between firing of the forward and rear charges.
The short time delay (less than 500 micro-seconds) tandem shaped charge warhead is well known in the prior art. Examples are U.S. Pat. Nos. 3,750,582 and 4,714,022. The techniques used in these inventions involve a forward charge followed by a blast shield which is in turn followed by a rear charge. In these devices the tandem warhead attacks military targets such as tanks as follows: the forward charge fires first and disrupts the outer armor of the target by causing reactive armor plates to initiate, by fracturing the laminate material in laminate (e.g., glass) armors, or by causing plate motion in bulging plate or (e.g. Chobham) armors. After a very short time delay, generally less than 500 microseconds, the rear charge fires and penetrates the remaining armor of the target and causes lethal damage to the occupants or interior components. During the time interval between the firing of the forward charge and the firing of the rear charge, the rear charge and its associated time delay system is protected from damage and/or premature detonation by a blast shield between the charges. As the time delay between the firing of the forward charge and the rear charge is increased (to 2000 microseconds and beyond), the blast shield must be made quite massive in order to protect the rearward components during the detonation of the high explosive of the forward charge, i.e. as the time delay is increased, so must the mass of the blast shield be increased in order to protect the rear charge from increased blast fragments and detonation products of the forward charge. The blast shield and the time delay must also be adjusted such that the blast shield remains out of the region required for jet formation of the rear charge. Thus, the rearward movement of the blast shield (caused by the explosive force of the forward charge) must be of relatively slow velocity, dependent not only upon the separation distance available between the rear charge and the blast shield but also the time delay required. The prior art generally slowed down the blast shield velocity by increasing its mass. This method resulted in a relatively heavy tandem warhead where long time delays (greater than 2000 microseconds) were necessary.